Load hoisting tackle



Feb. 28, 1967 v P. DURAND 3,

LOAD HOISTINGQTACKLE Filed Oct. 24, 1965 2 Sheets-Sheet 1 I INVENTOR 1/5695 fi k M BY ATTORNEYS Feb. 28, 1967 P. bURAND 3,306,469 LOADHOISTING TACKLE Filed Oct. 24, 1965 2 Sheets-Sheet 2 INVENTOR P/fgk:Amen/ 0 BY ATTORNEYS United States Patent Ofifice 3,306,469 PatentedFeb. 28, 1967 4 1 Claim. for. 212 71 My invention relates generallyspeaking to a tackle system similar to those used for hoisting loads,more particularly in the case of tower cranes and the like appliances.

On such apparatus, the loads are generally hoisted by means of tackleshaving a variable number of strands, generally two or four strands, soas to allow the operator to modify the hoisting force or speed.Generally such a change in the number of the strands is performed asillustrated in FIGS. 1 and 2 of the accompanying drawings by means of apulley P adapted to occupy two positions for one of which (FIG. 1) saidpulley engages the main tackle which corresponds to the case of atwo-stranded tackle, while the other position (FIG. 2) corresponds to asecuring of said pulley to the carriage C and consequently to afour-stranded tackle.

The passage from one position to the other is obtained by setting thecarriage C at a suitable point of the jib of the crane, after which thepulley block is brought into contact with the carriage C and means areoperated for the engagement or for the release of a pulley P as the casemay be. Said means are usually actuated starting from the operators cabthrough the agency of a mechanical control system and when the crane isno longer controlled from said cab, but say from ground or from somebuilding through an electric remote control system, the operator isconstrained to return into his cab so as to produce the desired changein the tackle and this increases the intricacy of the operation andleads obviously to a substantial loss of time.

My invention cuts out these drawbacks and allows ensuring said change inthe tackle by means of an arrangement carried by said tackle and adaptedto be controlled by a remote control system so as to be brought near anoperator located at any desired point.

It has consequently for its object a tackle system wherein the carriagefor the upper pulley is provided with a componud transverse strap ofwhich the flanges or sides are pivotally secured around two parallelspindles lying in their plans and are subjected to an elastic forcewhich urges them towards each other, said flanges defining thus togethera downwardly flaring opening while the main pulley block is equippedwith two symmetrical sloping members pivotally carried by transversespindles so that they may occupy two positions for one of which they areadapted to engage the gap between the flanges of the strap and for theother of which they lie outside the latter; furthermore, an axiallypulley block carries a transverse pin adapted to be raised and to engagesaid strap so as to allow duplication of the number of operativestrands.

My invention will be readily understood together with its advantages andfurther features from a reading of the following description, referencebeing made to the accompanying drawing illustrating by way ofexample'and in a non-limiting sense a preferred embodiment of myinvention as applied to a hoisting apparauts incorporating astrand-distributing carriage and tackle operating selectively with twoand four strands. In said drawings:

FIGS. 1 and 2 refer to prior art as already disclosed;

FIG. 3 is a side view of the system including the carriage and thetackle in its two-stranded condition;

FIGS. 4, 5 and 6 are front elevational views of the strap fitted on thecarriage and of the pulley blocks shown respectively for two strandedconditions of the tackle and for its four-stranded condition and duringthe pas: sage between the two conditions.

In FIG. 3, 2 designate the strand distributing carriage which carries inaccordance with my invention two parallel transverse spindles 3 to whichare pivotally secured two levers 4 interconnected by a spring urgingthem against the stop 6. Said levers 4 are provided with perforations 7registering with each other and form together a sort of strap theopening of which flares downwardly, as shown at 8, said flaring beingobtained by a bending of the outer ends of the levers 4 away from eachother.

The main or lower pulley block includes two parallel sloping memberspivotally carried by two coaxial transverse pivots 12. Said slopingmembers can occupy selectively two positions illustrated respectively insolid lines and in interrupted lines in FIG. 3.

As to the auxiliary pulley block 13, it carries above its pulley atransverse pin 14.

When the tackle operates with two strands as illustrated in FIGS. 3 and4, the auxiliary pulley block 13 engages the main pulley block 9, whilethe sloping members 10 occupy the position illustrated in solid lines.

When it is desired to set the tackle in its four-stranded condition, itis suflicient to operate as follows: the tackle being laid on the groundwith the sloping members 10 remaining in the solid line positionillustrated in FIG. 3, the circuit defining the upper end of the strokeis closed by the operator at the control station; after which saidoperator provides for the raising of the tackle up to its uppermostposition for which it engages the carriage 2. The pin 14 enters thus thegap between the two bent levers 4 which are urged apart thereby andcompress the spring 15, said levers returning into their former positionas soon as the pin 14 registers with and engages the perforations 7. Theauxiliary pulley block is thus in contact with the carriage 2 asillustrated in FIG. 5. The main pulley block 9 is then allowed to sink,whereby the formation of a four-stranded tackle is obtained.

When it is desired subsequently to return to a twostranded condition,the main pulley block 9 is lowered again onto ground surface and itssloping members are returned into the position illustrated ininterrupted lines in FIG. 3, the block being then raised in an emptycondition up to the carriage 2. Under the action of the sloping members10, which as illustrated in FIG. 6 engage the gap between the bentlevers 4 and the auxiliary pulley 13, the compound strap formed by saidlevers opens and releases thus the auxiliary pulley block 13 whichreturns into its lower position on the main pulley block 9. The tackleis then lowered onto ground surface. The sloping members are returnedinto their normal outwardly directed position illustrated in solid linesin FIG. 3.

Obviously, my invention is not limited to the sole embodiment describedand illustrated by way of example and it covers all the modificationsthereof falling within the scope of the accompanying claim.

What I claim is:

A load-hoisting tackle chiefly for tower cranes and the like appliancescomprising upper pulleys, a carriage carrying said upper pulleys, acompound strap including two downwardly flaring flanges separated by agap and adapted to pivot away from each other round horizontal axeslying in their planes and perpendicular to the axes of the upperpulleys, elastic means urging the lower ends of the flanges towards eachother, a main pulley block including at least one pulley and adapted tobe connected selectively through two strands and four strands with theupper pulleys and two sloping members arranged symmetrically to eithersides of a vertical plane perpendicular to the axis of the pulley of themain pulley block and adapted to rock each round a spindle parallel withlast-mentioned axis between an outwardly directed inoperative positionand an operative position for which said members are adapted to enterthe gap between the flanges of the strap to urge said flanges apart andan auxiliary pulley block including a pin parallel with the pulley axes,said auxiliary pulley block resting normally on the main pulley block toallow the latter to be connected through two strands with 10 the upperpulleys and being adapted, upon raising between the flanges of the strapand urging the latter apart to snap into an upper position on thecarriage to ensure a four-stranded connection with the main pulleyblock, the release of the auxiliary block being provided by the en-References Cited by the Examiner UNITED STATES PATENTS 840,676 1/1907Winnard et al. 254188 1,436,608 11/1922 Rodier 254l88 2,973,942 3/1961Sehaper 254188 FOREIGN PATENTS 171,531 10/1965 Russia.

ANDRES H. NIELSEN, Pnimary Examiner.

